[U-Boot] how to understand "uboot is 32bit program even it isin the 64bit mips"

[hacklu]

 thanks for you answer. I have got too much.

On 2011-06-22 13:25:34, Aaron Williams wrote:
>We have dealt with this in our release of U-Boot since we only support
>64-bit Linux. We use the n32 ABI with U-Boot and set it up to use a TLB
>entry to map U-Boot into a 32-bit addressable area.
  in the U-boot _shell_. I use md command. I found 
	md 0x100000 and mx0x800100000 are the same.
is that says:the virtual address 0x0 - 0xfffffff(256M, can I called this _kusg_ segment ?) 
are mapped to the _physical_ memory address 0x0 - 0xfffffff(256M) with the _TLB_.
and the virtual address 0x80000000 - 0x8fffffff(like that, _kseg0_ ?) is mapped to 
the _physical_ memory address 0x0 - 0xfffffff(256M) according to the mips
arch feature.
do I understand correctly?
>We have some special memcpy type routines that can handle the 64-bit
>addressing.

>All of our I/O registers require 64-bit addressing so we use assembly
>wrappers to do the actual read/writes to those addresses.

>-Aaron Williams

>On 06/21/2011 07:07 PM, hacklu wrote:
>>   I have a 64bit cnMips borad.In the mail list archives,it says  "uboot is 32bit,even in the 64bit cpu."
>> but how to understand that?
>> I have a guess,is the 64bit cpu support a 32bit-mode,then when does it switch to 64bit-mode to load 64-bit linux?
>>
>> btw,I have an other question,according to  <see mips run linux>,linux run in the _xkseg_ segment. so the first two bit >>virtual address in kernel space must be 11,
>> like 11xx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx (64bit).
>> but when I printf a variable' address in a foo driver,is say 0xa80000041c2ea180. not start of _11_.
>> the memory mapping mode has feazed me for _long_ _long_time.
I hope you can  answer this question for me. I really really want to know this.
thans for your attention.

>> Dear Wolfgang(or someone else who can anwser me),thanks 
>>  				
>>--------------
>> hacklu
>>2011-06-22
>>

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------------------				 
hacklu
2011-06-22